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H. S. Chawla G. Wenzel 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1987,74(6):841-845
Summary Calli derived from immature embryos of barley and wheat genotypes were screened for their resistance to purified culture filtrate produced by the fungus Helminthosporium sativum P.K. and B. Two selection methods were used: a continuous method in which four cycles of selection were performed one after another on toxic medium and a discontinuous method in which a pause on non-toxic medium was given after the second or third cycle of selection. The latter was superior as it allowed the calli to regain their regeneration ability. About 3,000 calli from two barley genotypes and 2,000 from two wheat genotypes were used for selection. The selection with the pathotoxins resulted in 6% to 17% surviving calli. Toxin tolerant callus lines of barley were characterised by protein isozymes. Zymograms showed one more isozyme than with the unselected sensitive callus. Barley and wheat plants have been regenerated from callus lines surviving the toxin treatment and in vivo testing against pathogen revealed that the majority of these plants were less sensitive. 相似文献
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Summary A study of the capacity ofExserohilum turcicum (Pass.) Leo. et Sug., to survive in sorghum field soil gave negative results, proving its inability to survive saprophytically in soil. That alternate graminaceous hosts and low seed-borne nature of the fungus might be involved in causing the seedling blight has been indicated.Deceased on 24th September 1982. 相似文献
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Helminthosporium euphorbiae is a pathogen of the weedEuphorbia heterophylla, which causes severe losses in soybean (Glycine max) crops. The fungus causes leaf loss and affects germination, making it a promising biocontrol agent for this weed. In order
to start a breeding program for this species, four isolates were examined for number of nuclei in the conidia and hyphae and
nuclear behavior at different cultivation stages. The conidia were multinucleated with about 20 nuclei per conidium, and 5
to 7 nuclei were observed in the hyphae compartments. The high number of nuclei makes the genetic manipulation of this species
diffucult, so the protoplast formation is an alternative for obtaining cells with a reduced number of nuclei. Thus the experimental
conditions for the production and regeneration of protoplasts inH. euphorbiae were determined by assessing three enzymatic complexes and seven osmotic stabilizers. The efficiency of formation and regeneration
frequency of the protoplasts varied depending on isolates, stabilizers and enzyme mixture used. The number of nuclei estimated
per protoplast was reduced to 1 to 6, depending on the stage of mycelial growth during the protoplast formation process. 相似文献
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D. H. Ling P. Vidhyaseharan E. S. Borromeo F. J. Zapata T. W. Mew 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1985,71(1):133-135
Summary Two R1 IR8 plants derived from somatic cells cultured in 25% Helminthosporium oryzae toxin-medium, and one IR54 plant derived from a control (toxin free medium) were found to have mutated resistance to brown spot disease of rice. In the second generation (R2, the offspring of the R1 generation) of the three resistant populations, the segregation of resistance and susceptibility to the disease was observed. This is the first report about a disease resistant mutation obtained successfully in rice by tissue culture and in vitro screening with phytotoxin.This research was conducted at the IRRI, Manila 相似文献
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Action spectra for the blue and near ultraviolet reversible photoreaction in the induction of fungal conidiation 总被引:1,自引:0,他引:1
Tadashi Kumagai 《Physiologia plantarum》1983,57(4):468-471
Induction of conidiation in Alternaria tomato (Cke.) Weber and Helminthosporium oryzae V. Breda de Haan was repeatedly controlled by ulternating doses of near ultraviolet light and blue light. These fungi did not form conidia in total darkness. However, when dark-grown colonies were exposed to near altraviolet light, conidiophore formation was induced, and conidia were then produced upon return to darkness. Conidiation was inhibited by blue light applied immediately after near ultraviolet light. Furthermore, the final response depended on the last kind of light received. The action spectrum for induction of conidiation showed a peak near 300 nm with a shoulder between 310 nm and 330 nm, as is common in photoconidiation of various fungi. The action spectrum for the reversion of induction of conidiation showed a peak near 447 nm with a shoulder between 400 nm and 440 nm, one minor peak around 478 nm and another one near 385 nm. This is very similar to the spectrum for the ubiquitous blue light receptor (cryptochrome). 相似文献
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Conidia of Helminthosporium teres had negligible difference in germination and germ tube length between the decolorized and non-decolorized host leaves. Appressoria, penetration and colonization were less on decolorized host leaves, but addition of exogenous nutrients stimulated these stages. Leached conidia had reduced germination on decolorized host leaves, while appressoria formation, penetration and colonization were negligible. The addition of nutrients in the external environment, however, enabled some of the leached conidia to penetrate and colonize. Stimulation by the exogenous nutrients in decreasing order were: sucrose > glucose > yeast extract > leaf leachates. Optimum levels for various nutrients tested were 2% (w/v) each of sucrose and glucose, and 0.1% (w/v) yeast extract. Higher concentrations inhibited these stages of infection. Leached conidia and decolorized leaves had smaller amounts of carbohydrates than non-leached conidia and non-decolorized leaves, respectively. Depletion of host carbohydrates reduced appressoria formation, penetration and colonization and loss of carbohydrates from spores reduced germination. 相似文献